[dm-devel] Integrity discard/trim extremely slow on NVMe SSD storage (~10GiB/minute)

[Melvin Vermeeren]

Hi again,

On Friday, 30 April 2021 21:26:23 CEST Melvin Vermeeren wrote:
> (As mentioned in other mail I
> contacted Seagate about this, it should be fixed in drive firmware.)

After some back and forth with testing and diagnostics Seagate has provided 
updated firmware version STNSC016, drives originally had version STNSC014. 
Updating this firmware with nvme-cli utilities has resolved the issue.

For validation, I allocated 500GiB space for testing in the full stack:
FireCuda 520 -> dm-integrity -> mdadm raid1 -> luks cryptsetup -> lvm -> lv

Then I discard the LV. Disk util % of both drives moves to 100% while 
discarding, as checked with dstat. It took 20.920s real seconds to discard 
500GiB on a live system.

With old firmware, rate with this workload was approx 10GiB per 70 seconds or 
so. This means the new firmware is approx (500/10) * (70/20.92) = 167.3 times 
faster in this workload with a rate of approx 1434GiB per minute.

Perhaps there are still optimisations possible for dm-integrity, but in this 
case it really was a device issue as you suspected. Thanks again for all the 
help and work on dm-integrity!

Cheers,

-- 
Melvin Vermeeren
Systems engineer
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